Objective To explore the occurrence and clinical characteristics of thyroid dysfunction caused by programmed death-1 (PD-1) inhibitors produced in China in the real world.

Methods Solid tumor patients treated with domestic PD-1 inhibitors in the oncology department of The Third People's Hospital of Bengbu from January 2022 to May 2024 were selected, and their general information, medication use of domestic PD-1 inhibitors, combination therapy use, and types of thyroid dysfunction caused by domestic PD-1 inhibitors were recorded. The causal relationship between domestic PD-1 inhibitors and thyroid dysfunction was evaluated using Naranjo adverse drug reaction probability scale, and the occurrence and clinical characteristics of thyroid dysfunction cases based on the medical records of those whose evaluation results were "definite", "probable", and "possible".

Results A total of 55 patients were included, of which 27 cases (49.09%) had thyroid dysfunction, including 6 cases with subclinical hypothyroidism at baseline, and the remaining 21 cases with normal thyroid function at baseline. Abnormal thyroid function included 4 cases of hyperthyroidism, 10 cases of hypothyroidism, 5 cases of subclinical hyperthyroidism, and 8 cases of subclinical hypothyroidism; 21 cases occurred within 3 medication cycles. The severity of all thyroid dysfunction was grade 2 or below, with no obvious clinical symptoms, only 1 case with mild palpitations and 4 cases with mild fatigue.

Conclusions Thyroid dysfunction is one of the frequently occurring immunotherapy-related adverse events in the treatment of solid tumors by PD-1 inhibitors. Among them, the incidence of hypothyroidism and subclinical hypothyroidism is higher, the severity is mostly below grade 2, the clinical symptoms are not obvious, and the prognosis is generally good. However, when using domestic PD-1 inhibitors, it is still necessary to strengthen monitoring of thyroid function and provide early intervention in order to better ensure the medication safety of patients.